from kivy.uix.boxlayout import BoxLayout
from kivy.uix.progressbar import ProgressBar

class playprogressbar_layout( BoxLayout ):
    def __init__( self, **kwargs ):
        super( playprogressbar_layout, self ).__init__( **kwargs )
        pb = ProgressBar( max = 100 )
        self.add_widget( pb )
        
if __name__ == '__main__':
    from kivy.app import App
    class testApp( App ):
        def build( self ):
            return playprogressbar_layout()
      
    testApp().run()